The invention relates to a shifting arrangement for the exact space positioning of a writing carriage in tele- or data typewriters in which the writing carriage is moved alongside of a record holder with the aid of a stepping motor.
Generally, the writing carriage in tele- or data typewriters is moved alongside of a record holder for each line with the aid of a driving device according to pulses of a positioning pattern. Such a positioning pattern denotes the distance between the individual characters in a printed line. Due to the gradual advance needed, stepping motors are particularly suited as driving means since they can be digitally triggered in simple fashion via counting devices. When loading of the stepping motor occurs between the rotary field and the armature driving the writing carriage, an angle displacement, the so-called load angle results, thus requiring special techniques for triggering the stepping motor.
In a related case, German Offenlegungsschrift No. 1,563,019 (having no U.S. corresponding application), a method and an arrangement for stepping of electrical stepping motors is described in which the rapid execution of step-like rotary motions of motors with subsequent overshot-free stopping is performed. The field winding of the electrical stepping motor is successively excited with a sequence of impulses whose length and amplitude are adjusted to the rotary motion in such a manner that the stepping motor driver lags behind the exciter field in the acceleration period, runs ahead of the exciter field in the subsequent deceleration period, and is finally stopped by the exciter field in the rest position until the beginning of the next step-like rotary motion.